Obesity and its attended disorders, such as Type II diabetes, have reached epidemic proportions. We previously demonstrated that inhibition of fatty acid synthase (FAS) with C75, a synthetic FAS inhibitor, is anorexogenic and induces significant weight loss. This grant is one of a series of three proposals put forth by our FAS Working Group whose overall goal is to determine how C75 and related classes of compounds mediate their effects. The goal of this proposal is to investigate the cellular mechanisms of actions of C75. FAS catalyzes long chain fatty acid synthesis through a complex seven step condensation reaction that utilizes acetyI-CoA, malonyI-CoA, ATP, and NADPH to generate palmitate. Our hypothesis is that C75 has both central and peripheral actions to modulate body weight. Centrally, C75 alters the metabolisms of neurons including those in hypothalamic feeding pathways to modulate gene expression and influence feeding behavior. Peripherally, C75 acts to increase energy utilization by stimulating carnitine palmitoyl transferase-1 (CPT-1) the enzyme that imports palmitate into the mitochondrion for beta-oxidation. Our hypothesis in this proposal is that C75 alters neuronal metabolism to modulate neuronal signaling pathways, leading to a change in energy perception by the cell. We pose three testable hypotheses regarding the effect of C75 on neuronal metabolism. Specific Aim I will test the hypothesis that FAS inhibition alters neuronal metabolism. We will employ in vitro approaches using primary cultures of cortical neurons, hypothalamic neurons, and the 3T3-L1 cell pre-adipocyte cell line to perform biochemical and molecular assays to understand how FAS inhibition effects neuronal energy flux and enzyme activities. In Aim II we will test the hypothesis that these metabolic changes influence signaling pathways. We will use Western blot analysis and antibodies to signaling cascade proteins, as well pharmacological agents that allow us to selectively modify pathways to determine the effect of FAS inhibition on important cellular substrates such as AMP kinase, uncoupling proteins, and peroxisomes. In Aim III we will test the hypothesis that those pathways are relevant in vivo by modulating these signaling pathways in the presence of C75 and determining which pathways affect feeding and weight loss. [unreadable] [unreadable] [unreadable]